The AMD HD6990 is a dual 2nd-generation DirectX 11 GPU armed with 4GB of GDDR5. The AMD HD6990 is also equipped with 3,072 Stream processors, 64 ROPs and a variable clock speed from 830MHz to 880MHz with the flick of a switch. With two monstrous Cayman XT GPUs, the AMD HD 6990 requires an equally strong cooling solution so it is equipped with a pair of vapor chamber heatsinks with phase-change thermal compounds and a centrally mounted blower-style fan that drives the heat out the back and front of the AMD HD6990.